|Publication number||US6850761 B2|
|Application number||US 09/194,297|
|Publication date||Feb 1, 2005|
|Filing date||May 26, 1997|
|Priority date||May 27, 1996|
|Also published as||CN1220069A, EP0894406A1, US20020002066, WO1997046034A1|
|Publication number||09194297, 194297, PCT/1997/318, PCT/FI/1997/000318, PCT/FI/1997/00318, PCT/FI/97/000318, PCT/FI/97/00318, PCT/FI1997/000318, PCT/FI1997/00318, PCT/FI1997000318, PCT/FI199700318, PCT/FI97/000318, PCT/FI97/00318, PCT/FI97000318, PCT/FI9700318, US 6850761 B2, US 6850761B2, US-B2-6850761, US6850761 B2, US6850761B2|
|Original Assignee||Nokia Corporation|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (28), Non-Patent Citations (1), Referenced by (24), Classifications (10), Legal Events (5)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The invention relates to a method for determining the position of a mobile station located in the coverage area of a base station in a radio system, in which method the base station comprises equipment for receiving signals from the same mobile station simultaneously by at least two antenna beams directed in different directions, and in which method: the signal levels of the signals received by the different antenna beams are measured, the signal levels of the signals received from the same mobile station by the different antenna beams are compared, and the direction to the mobile station in relation to the base station is determined on the basis of the relations between the signal levels measured for the different antenna beams. The invention further relates to a base station of a radio system, which base station comprises antenna equipment for receiving signals from a certain mobile station simultaneously by at least two antenna beams directed in different directions, measuring equipment for measuring the signal levels of the signals received by the different antenna beams, calculation means which are responsive to the measuring equipment for determining the direction from the base station to the mobile station on the basis of the relations of the signal levels measured for the different antenna beams, and equipment for defining a timing advance for the mobile station, which is in radio connection with the base station, to compensate for a time lag caused by the distance between the mobile station and the base station.
By the notion antenna beams turned in different directions is here meant that the radio cell covered by the base station is divided into adjacent sectors from which signals related to the same logical channel (the same frequency channel and time slot) are received, and that a directional antenna or the equivalent is directed to each sector, by which antenna signals can be received from the sector in question. The antennas of the base station are, however, preferably directed so that they overlap at least partly in the border zones between them.
The invention relates to determining of the position of a mobile station in a cellular radio system, e.g. the GSM system (Groupe Special Mobile). Prior solutions are known where the position of the mobile station has, for example, been determined by checking from the home location register (HLR) of the mobile switching centre of the GSM-system in which radio cell the mobile station is located at a certain moment. The most significant problem with this known solution is its inaccuracy. Since it can only be ascertained in which radio cell the mobile station is located in the known solutions mentioned before, the accuracy of determining the position, of course, directly depends on the size of the radio cell in question. The size of the radio cells again totally depends on the properties of the radio system, but in the GSM system, for example, the inaccuracy of determining the position according to the radio cell can typically be several kilometers.
However, in practice there has been a need for greater accuracy in determining the position of a mobile station. For example in connection with handover operations it would be necessary to determine the exact geographical position of the mobile station. At present handover is, for instance in the GSM system, based on the signal level and quality of the signals received, and by no means on the position of the mobile station. Thus temporary radio disturbances can lead to an unnecessary handover operation, i.e. the mobile station is transferred from one cell to another when the signal level or quality falls below a predetermined level, after which the handover operation is repeated but in the reverse direction, i.e. the mobile station is returned to the original cell when the disturbance is over
Another situation where it would be necessary to determine the exact position of the mobile station is when a stolen mobile station or for example a SIM Card (Subscriber Identity Module) is to be located. In known solutions, where the inaccuracy in locating the mobile station is several kilometers, it is practically impossible to determine the position of a stolen mobile station.
The object of the present invention is to solve the above mentioned problems and to achieve a more precise method for determining the position of a mobile station. This aim is achieved by the method of the invention, which is characterized in calculating the distance from the mobile station to the base station on the basis of a timing advance given to the mobile station by the base station and the propagation speed of the radio signals.
The invention also relates to a base station by which the method of the invention can be carried out. A base station according to the invention is characterized in that the calculation means comprise equipment for calculating the distance between the base station and the mobile station on the basis of the timing advance defined for the mobile station and the propagation speed of the radio signals.
The invention is based on the realization that the position of the mobile station can be determined with significantly greater accuracy than in known solutions when its signals are received by at least two antenna beams directed in different directions and when the audibility of the signals received by the respective beams from the mobile station is compared. In other words, the audibility of the signals transmitted by the mobile station is normally best for the beam that is directed straight towards the mobile station. Thus it can be determined within which beam the mobile station is located. When it is further known in which direction the beam in question is turned the direction to the mobile station can easily be determined. How near the centre or respectively the edges of the beam the mobile station is located can be determined by comparing the signal levels of the signals received by the beam in question to the signal levels of the signals received by “the principal beam”. Thus the direction from the base station to the mobile station can be determined from the relation between the signal levels of the signals received by the respective beams. In addition to this the distance from the mobile station to the base station can, according to the invention, be calculated on the basis of a timing advance given to the mobile station by the base station and the propagation speed of the radio signals. In the GSM system, for example, there is already in use a so called timing advance TA given by the base station to the mobile station to inform it of how much in advance it should transmit its signals so that the signals will arrive at the right moment and in the proper time slot to the base station regardless of the distance between the mobile station and the base station. Thus, the distance between the base station and the mobile station can be determined on the basis of the timing advance when the propagation speed of the signals is known.
The most significant advantage with the solution of the invention is thus that the position of the mobile station, that is both its direction and distance from the base station, can be determined with significantly greater accuracy than previously, which among other things makes it possible to make handover decisions on the basis of the location of the mobile station, whereby unnecessary handover operations can be avoided, and for example to locate a stolen mobile station with greater accuracy than before.
So that temporary disturbances would not significantly disturb the determining of the position of the mobile station, in a preferred embodiment of the invention the mean value of the signal levels of the signals received by the respective antennas from a certain mobile station is calculated for a certain time period, whereby the position of the mobile station is determined on the basis of the mean values of the calculated relations.
The preferred embodiments of the method and base station of the invention are revealed in the attached dependent claims 2-4 and 6-8.
In the following the invention will be described in more detail in a few preferred embodiments by mean of the attached drawings, in which
In block A signals are received from a mobile station MS by several antenna beams directed in different directions. The antenna beams used are preferably relatively narrow beams that are directed so that they at least partly overlap (compare with FIG. 2).
In block B the received signal strength indication RSSI of the received signal is measured for the signals received by the respective beams.
In block C a mean value is calculated for the RSSI values measured within a certain time span for each beam. By calculating the mean value for the RSSI values it can be avoided that temporary disturbances influence the locating of the mobile station. For example in the GSM system the time span in question can be chosen so that the mean value is calculated for a few bursts received from the mobile station.
In block D a first beam is chosen which has the highest RSSI mean value (=RSSI1). In addition to this at least one of the adjacent beams is chosen as a second beam, whereby preferably the beam with the higher RSSI mean value (=RSSI2) is chosen.
In block E the RSSI values for the different beams are compared by calculating the ratio of the RSSI mean values RSSI1/RSSI2 for the chosen beams.
In block F it is checked if the RSSI ratio for the beams is greater than the predetermined reference value K. The reference value is chosen so that it is essentially greater than 1. If the RSSI ratio exceeds the reference value that denotes that the audibility of the mobile station is much better by the first chosen beam than by the second chosen beam, which means that the mobile station is located in the direction of the centre of the first beam. Hereby a transfer is made to block G, where the direction of the first chosen beam is specified, which is the direction where the mobile station is located.
In block H it is checked if the RSSI ratio is nearly 1. If that is the case it denotes that the audibility of the mobile station is almost equally good via both the chosen beams. This again means that the mobile station is located in the border zone between the two beams. Hereby a transfer is made to block I, where the direction is specified where the border zone between the beams (and the mobile station) is located.
Provided that the RSSI ratio of the beams is not greater than the reference value K, neither the RSSI ratio nearly 1, a transfer is made to block J. Thus it is ascertained that the audibility of the mobile station is somewhat better via the first chosen beam than via the second chosen beam, which means that the mobile station is located between the centre of the first chosen beam and the border zone between the chosen beams. If it is necessary to determine the direction to the mobile station more accurately than that, the direction in question can be determined by the RSSI ratio of the beams. That requires measurements made in advance so that a precise picture can be had of how the RSSI ratio between the beams changes when the mobile station moves from the border zone between the beams to the centre of the first beam.
By following the flowchart in
distance=timing advance*propagation speed of the radio signals
How accurately the position of the mobile station can be determined in relation to the base station of course depends on the width of the antenna beams used and how accurately the base station calculates the timing advance for the mobile station. For example in the GSM system the position of the mobile station can be determined as described above with an accuracy of typically about 0.5×0.5 km, when the width of the antenna beams is about 30°.
The mobile station MS of
If the mobile station is located in the border zone A2 between the beams the base station will recognize that as the RSSI values calculated for beams 1 and 2 are essentially as great, that is the RSSI ratio is nearly 1.
If the mobile station is located between the centre A1 of beam 1 and the border area between beams 1 and 2, that is in the area A3, the base station will recognize that as the RSSI values measured for beam 1 are somewhat greater than the RSSI values measured for beam 2.
In the example in
If such a receiver is used that can manage diversity reception, the RSSI receiver can have two outputs, whereupon the RSSI receiver chooses the two best antenna beams for use and transmits the signals received by these further to the actual receiver of the base station. With an arrangement like this an improvement of about 3 dB can be achieved in the reception of signals from a mobile station in the border zone between the sectors.
According to the invention the RSSI receiver 8 feeds the RSSI values measured for the respective beams to the calculator 9. The calculator 9 can for example be a processor and a computer program added to the base station for locating the mobile station.
The calculator 9 calculates the mean value of the received signals for each antenna beam on the basis of the measuring results. Since the base station in
A signal denoting the timing advance TA given to the mobile station by the base station is according to the invention also fed to the calculator 9. On the basis of this signal the calculator calculates the distance to the mobile station as described in connection with the flowchart in FIG. 1.
The signal POS fed from the output of the calculator thus denotes the position of the mobile station in relation to the base station (direction+distance). For instance handover operations can be timed better on the basis of this information, since they are then based on information about the position of the mobile station. Additionally the information about the position of the mobile station can be transmitted further via the base station controller and the mobile switching centre to the network management centre, whereupon the operator can determine the position of the mobile station with even greater accuracy from the network management centre.
It is to be understood that the above description and the related drawings are only intended to illustrate the present invention. Thus the invention can also be applied in other cellular radio systems than the GSM system. To those skilled in the art various other modifications and variations of the invention will be apparent within the scope and spirit of the present invention disclosed in the attached claims.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US4163978||Nov 29, 1977||Aug 7, 1979||The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland||Radio direction finding|
|US5394158||Jul 25, 1991||Feb 28, 1995||British Telecommunications Public Limited Company||Location determination and handover in mobile radio systems|
|US5418843 *||Jun 24, 1993||May 23, 1995||Televerket||Method for estimating traffic density in mobile telephone networks|
|US5432842 *||Mar 17, 1992||Jul 11, 1995||Hitachi, Ltd.||Mobile communication switching across cell boundaries|
|US5508707||Sep 28, 1994||Apr 16, 1996||U S West Technologies, Inc.||Method for determining position by obtaining directional information from spatial division multiple access (SDMA)-equipped and non-SDMA-equipped base stations|
|US5515419||Aug 2, 1994||May 7, 1996||Trackmobile||Tracking system and method for tracking a movable object carrying a cellular phone unit, and integrated personal protection system incorporating the tracking system|
|US5612703 *||May 19, 1995||Mar 18, 1997||Celsat America, Inc.||position determination in an integrated cellular communications system|
|US5657487 *||Jun 5, 1995||Aug 12, 1997||Airnet Communications Corporation||Mobile telephone location process making use of handoff data|
|US5884147 *||Jan 3, 1996||Mar 16, 1999||Metawave Communications Corporation||Method and apparatus for improved control over cellular systems|
|US5884164 *||Oct 7, 1997||Mar 16, 1999||France Telecom||Call handover in a non-geostationary satellite constellation|
|US5893033 *||May 23, 1996||Apr 6, 1999||Nokia Telecommunications: Oy||Methods for making a faster handover, and a cellular radio systems|
|US5966670 *||May 23, 1996||Oct 12, 1999||Nokia Telecommunications Oy||Method for transmitting a pilot signal, and a cellular radio system|
|US5970413 *||Jun 6, 1996||Oct 19, 1999||Qualcomm Incorporated||Using a frequency that is unavailable for carrying telephone voice information traffic for determining the position of a mobile subscriber in a CDMA cellular telephone system|
|US6021329 *||May 1, 1997||Feb 1, 2000||Telefonaktie Bolaget Lm Ericsson (Publ)||Method, and associated apparatus, for determining cell relationships in a radio communication system|
|US6034635 *||Jun 6, 1996||Mar 7, 2000||Gilhousen; Klein S.||Method for using only two base stations for determining the position of a mobile subscriber in a CDMA cellular telephone system|
|US6049718 *||Jul 29, 1997||Apr 11, 2000||Stewart; Gordon M.||Telephone system and method with background location response capability|
|US6061337 *||Dec 2, 1996||May 9, 2000||Lucent Technologies Inc.||System and method for CDMA handoff using telemetry to determine the need for handoff and to select the destination cell site|
|US6061564 *||Sep 30, 1997||May 9, 2000||Nec Corporation||Mobile communication device|
|US6075993 *||Nov 14, 1995||Jun 13, 2000||Sony Corporation||Personal station and information providing system|
|US6108556 *||Jan 30, 1998||Aug 22, 2000||Matsushita Electric Industrial Co., Ltd.||Method and system for locating a mobile station|
|US6122260 *||Dec 16, 1996||Sep 19, 2000||Civil Telecommunications, Inc.||Smart antenna CDMA wireless communication system|
|EP0320913A2||Dec 14, 1988||Jun 21, 1989||Nokia-Mobira Oy||A method for locating a mobile station, as well as a mobile station and a base station for carrying out the method|
|EP0431956A2||Dec 7, 1990||Jun 12, 1991||Motorola, Inc.||Cellular radiotelephone diagnostic system|
|EP0631453A2||Jun 2, 1994||Dec 28, 1994||Telia Ab||Method for locating mobile stations in a digital telephone network|
|GB2224409A||Title not available|
|GB2243041A||Title not available|
|GB2253758A||Title not available|
|WO1996007108A1||Jun 30, 1995||Mar 7, 1996||Motorola Inc||Method and apparatus for conveying a communication signal between a communication unit and a base site|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US6993361 *||Nov 27, 2002||Jan 31, 2006||Interdigital Technology Corporation||System and method utilizing dynamic beam forming for wireless communication signals|
|US6999795||Nov 27, 2002||Feb 14, 2006||Interdigital Technology Corporation||System and method utilizing dynamic beam forming for wireless communication signals|
|US7016702||Nov 27, 2002||Mar 21, 2006||Interdigital Technology Corporation||System and method utilizing dynamic beam forming for wireless communication signals|
|US7092673 *||Dec 27, 2002||Aug 15, 2006||Nortel Networks Limited||Angle of arrival estimation in a wireless telecommunications network|
|US7139593 *||Dec 14, 2001||Nov 21, 2006||Samsung Electronics Co., Ltd.||System and method for improving performance of an adaptive antenna array in a vehicular environment|
|US7181244 *||Nov 15, 2001||Feb 20, 2007||Qualcomm, Incorporated||Method and apparatus for using position location to direct narrow beam antennas|
|US7657288 *||Dec 22, 2005||Feb 2, 2010||Interdigital Technology Corporation||System and method utilizing dynamic beam forming for wireless communication signals|
|US8055300||Aug 29, 2007||Nov 8, 2011||Telefonaktiebolaget Lm Ericsson (Publ)||System and method for indoor coverage of user equipment terminals|
|US8078146 *||Jun 1, 2007||Dec 13, 2011||Honeywell International Inc.||Systems and methods for security and asset management|
|US8311558||Mar 22, 2010||Nov 13, 2012||Buzby Networks, Llc||Real-time network node location system and method|
|US8519889 *||Jul 21, 2009||Aug 27, 2013||Research In Motion Limited||Method and apparatus for estimating location of a wireless station using multi-beam transmission|
|US8970432||Nov 28, 2011||Mar 3, 2015||At&T Mobility Ii Llc||Femtocell calibration for timing based locating systems|
|US8996031||Apr 19, 2013||Mar 31, 2015||At&T Mobility Ii Llc||Location estimation of a mobile device in a UMTS network|
|US9008684||Oct 28, 2011||Apr 14, 2015||At&T Mobility Ii Llc||Sharing timed fingerprint location information|
|US9008698||May 15, 2014||Apr 14, 2015||At&T Mobility Ii Llc||Location analytics employing timed fingerprint location information|
|US9009629 *||Dec 1, 2010||Apr 14, 2015||At&T Mobility Ii Llc||Motion-based user interface feature subsets|
|US9026133||Nov 28, 2011||May 5, 2015||At&T Mobility Ii Llc||Handset agent calibration for timing based locating systems|
|US9046592||Jun 13, 2012||Jun 2, 2015||At&T Mobility Ii Llc||Timed fingerprint locating at user equipment|
|US9053513||Aug 5, 2011||Jun 9, 2015||At&T Mobility Ii Llc||Fraud analysis for a location aware transaction|
|US9094929||Jun 12, 2012||Jul 28, 2015||At&T Mobility Ii Llc||Event tagging for mobile networks|
|US9103690||May 13, 2014||Aug 11, 2015||At&T Mobility Ii Llc||Automatic travel time and routing determinations in a wireless network|
|US20040127230 *||Dec 27, 2002||Jul 1, 2004||David Bevan||Angle of arrival estimation in a wireless telecommunications network|
|US20120144346 *||Dec 1, 2010||Jun 7, 2012||At&T Intellectual Property I, L.P.||Motion-based user interface feature subsets|
|CN101965050B *||Jul 21, 2010||Dec 24, 2014||黑莓有限公司||Method and apparatus for estimating location of a wireless station using multi-beam transmission|
|U.S. Classification||455/437, 455/456.1, 455/440|
|International Classification||G01S5/02, G01S3/28, H04W64/00|
|Cooperative Classification||G01S3/28, H04W64/00|
|European Classification||H04W64/00, G01S3/28|
|Feb 16, 1999||AS||Assignment|
Owner name: NOKIA TELECOMMUNICATIONS OY, FINLAND
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:PALLONEN, JORMA;REEL/FRAME:009767/0552
Effective date: 19981110
|Jul 16, 2008||FPAY||Fee payment|
Year of fee payment: 4
|Sep 17, 2012||REMI||Maintenance fee reminder mailed|
|Feb 1, 2013||LAPS||Lapse for failure to pay maintenance fees|
|Mar 26, 2013||FP||Expired due to failure to pay maintenance fee|
Effective date: 20130201